NEW YORK (Reuters Health) - During their child's first two months of life, most new mothers have concerns about breastfeeding that make them consider giving up and switching to formula, according to a new study.

Ninety-two percent of mothers surveyed when their baby was three days old were worried about breastfeeding - for example, that they weren't making enough milk or that the infant wasn't latching on well.

That proportion fell over time, but the majority of women continued to have reservations about breastfeeding for months after their baby's birth, researchers report Monday in Pediatrics.

"We were surprised by the large number of concerns mothers had, and we were very concerned by how particular concerns were strongly related to giving up with breastfeeding" - such as worries about babies not getting enough nutrition, said Laurie A. Nommsen-Rivers, the study's senior author, from Cincinnati Children's Hospital Medical Center.

Dr. Lori Feldman-Winter, a pediatrician at Cooper University Hospital in Camden, New Jersey, did not think the findings were surprising. But they are "alarming" in light of all the resources the United States has put into promoting breastfeeding at the hospital level, she told Reuters Health.

"My sense is in my gut that the ability for moms to find adequate breastfeeding support in the community is very variable and in many communities non-existent," Feldman-Winter, who also chairs the policy committee for the American Academy of Pediatrics Section on Breastfeeding, said.

"We're going to have many women really wanting to breastfeed and encountering difficulties."

The World Health Organization recommends exclusive breastfeeding - without any formula or solid food - until a baby is six months old, followed by continued breastfeeding with the addition of appropriate foods through age two.

Data from the Centers for Disease Control and Prevention show more than three quarters of U.S. women start breastfeeding and more than half of week-old babies have only had breast milk.

Just 16 percent of infants are exclusively breastfed for six months, however.

For the new study, the researchers surveyed 532 first-time mothers-to-be from one medical center about their plans for breastfeeding, then interviewed them six more times: when their baby was just born and when it was 3, 7, 14, 30 and 60 days old.

During those interviews, women raised 49 unique breastfeeding concerns, a total of 4,179 times. The most common ones included general difficulty with infant feeding at the breast - such as an infant being fussy or refusing to breastfeed - nipple or breast pain and not producing enough milk.

Between 20 and 50 percent of mothers stopped breastfeeding altogether or added formula to the mix sooner than they had planned to do when they were pregnant.

Of the 354 women who were planning to exclusively breastfeed for at least two months, for example, 166 started giving their babies formula between one and two months.

And of 406 women who had planned to at least partially breastfeed for two months, 86 stopped before then.

New mothers who expressed concerns at day 3 were three times more likely to start giving formula before two months and nine times more likely to stop breastfeeding altogether, compared to the small group of women who had no concerns.

"It's a shame that those early problems can be the difference between a baby only getting breast milk for a few days and going on to have a positive breastfeeding relationship for a year or longer," Nommsen-Rivers told Reuters Health.

"If we are able to provide mothers with adequate support, 95 percent of all breastfeeding problems are reversible."

Although the U.S. has gotten better about promoting breastfeeding in the hospital, she said, there is a "tremendous gap in care" when women are discharged.

"It can be very overwhelming, those first few days at home," Nommsen-Rivers said.

She recommended women take time during their pregnancy to find both friends and professional resources in the community where they can turn if they find breastfeeding challenging.

Feldman-Winter, who was not involved in the new research, said new mothers who are having trouble can also call the hospital where they delivered to get a referral for support. Ideally, she said that support could be integrated into care at the pediatrician's office.

"The goal should be to support continued exclusive breastfeeding," she said.

Most of all, Nommsen-Rivers said, new mothers should know that "they're not alone, and it's really common to struggle in those first few days."